The critical dimension (CD) of a feature on a semiconductor wafer is the width of that feature. The pitch is generally defined as the critical dimension plus the distance to the next feature.
For semiconductor processing methodology using etch techniques, a photoresist layer is deposited on top of a material to be etched. The photoresist layer defines the desired features, masking the portion of the layer which is not to be etched and leaving exposed the portion to be etched. During the etching process, materials from a portion of the layer which is etched as well as compounds formed by a combination of the etchant gases and the materials of the layer to be etched, can tend to coat the sides of the desired feature and thereby increase the critical dimension of the feature beyond that defined immediately under the photoresist mask. Such growth of the critical dimension can disadvantageously diminish the distance between the features and adversely affect the functionality of the features.
Accordingly, there is a need to provide a semiconductor processing methodology which allows for the desired features to be appropriately etched without causing a growth of the critical dimension of the feature during the etching process.